Pass....Accuphase....or......

@southofdallas Class A means the output device or devices never go into cutoff.

There are class A push-pull amps and class A single-ended amps, which might be tube or solid state.

Class A is used to get more linearity out of the output section of the amp. If the amp is zero feedback this is pretty important. But depending on how much feedback is used it might be a lot less important, especially in modern designs where more feedback is possible.

Topping makes a line of class B amplifiers now that have exceedingly low distortion. From a designer's point of view, you use class A to reduce distortion, so in a way we can now see that the class of operation is far less important than it used to be. There are class D amps now that easily challenge any class A amp ever made.

If the amp is to be musical, IOW easy to listen to while being neutral, what is far more important is if the amp brings home the bacon in that regard rather than its class of operation! IOW there is far too much emphasis on the class of operation; probably that was important 30-40 years ago but no longer.

"Class A means the output device or devices never go into cutoff.” - definition is correct!

push-pull A class amps have bias to cover max current for loads, supported by class a! if load is lower than nominal, one of devices indeed goes into cutoff!

@atmasphere "There are class D amps now that easily challenge any class A amp ever made."

Sorry but I just have to ask.... Why do we rarely or never see the power specs of Class D amps below 4 Ohms? Atma Sphere class D is 100 watts per channel into 8 Ω and 200 watts per channel into 4 Ω.... and then? Many 4 Ohm speakers drop way under that. Do they clip? Crash or explode?;)

if load is lower than nominal, one of devices indeed goes into cutoff!

@westcoastaudiophile That's true of a single-ended class A amp too.

@southofdallas Our amps have an over-current protection circuit that shuts the amp down if too much current shows up. Its got no problem driving 2 Ohms other than that. For example if there is a dip in impedance to 2 Ohms, if the speaker is an ESL that drops to 2 Ohms in the highs its no worries.

@atmasphere "Our amps have an over-current protection circuit that shuts the amp down if too much current shows up."

The speakers I had before (Elipsa SE) went down to around 2 ohms at 100 Hz. It is a big difference then between shutting down and doubling the delivered power to 1 ohm or less. Of course, we are talking about twice the price maybe....and maybe class d is aimed at high efficiency speakers....but still. I can understand why some audiophiles are still buying heavy amps.